I've been running TPT's in my vintage steel Centurion Ironman. The tubes are pretty small & fit inside the 700x25mm tires well. I'm satisfied. Haven't had a flat in over 3000 miles. Really like them when I'm approaching 40mph on a steep downhill. I'm running ordinary Michelin Dynamic sport tires inflated to 100psi. I really can't tell the difference between the TPT's & regular tubes. Don't understand why so many on these boards have such a low opinion of them.